#!/bin/bash

#Copyright 2017 Daniele Fucini <dfucini@gmail.com>

#This program is free software: you can redistribute it and/or modify
#it under the terms of the GNU General Public License as published by
#the Free Software Foundation, either version 3 of the License, or
#(at your option) any later version.

#This program is distributed in the hope that it will be useful,
#but WITHOUT ANY WARRANTY; without even the implied warranty of
#MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#GNU General Public License for more details.

#You should have received a copy of the GNU General Public License
#along with this program.  If not, see <http://www.gnu.org/licenses/>.

#Simple backup script. Reads options, sources and destination from a configuration file or standard input

#Help function
function help_function {
   echo "simple_backup, version 1.3.4"
   echo ""
   echo "Usage: $0 [OPTIONS]"
   echo ""
   echo "Options:"
   echo "-h, --help                             Print this help and exit."
   echo "-c, --config      CONFIG_FILE          Use the specified configuration file"
   echo "                                       instead of the default one."
   echo "                                       All other options are ignored."
   echo "-i, --input       INPUT [INPUT...]     Specify a file/dir to include in the backup."
   echo "-d, --directory   DIR                  Specify the output directory for the backup."
   echo "-e, --exclude     PATTERN [PATTERN...] Specify a file/dir/pattern to exclude from"
   echo "                                       the backup."
   echo "-k, --keep        NUMBER               Specify the number of old backups to keep."
   echo "                                       Default: keep all."
   echo "-u, --user        USER                 User performing the backup."
   echo "                                       Default: current user."
   echo "                                       WARNING: This currently doesn't work with"
   echo "                                       other options!"
   echo ""
   echo "If no option is given, the program uses the default"
   echo "configuration file: $HOMEDIR/.simple_backup/config."
   echo ""
   echo "Report bugs to dfucini@gmail.com"
   exit 0
}

#Read configuration file
function read_conf {
   if [[ "$#" -eq 0 ]]; then
      CONFIG="$HOMEDIR/.simple_backup/config"
      
      if [[ ! -f "$CONFIG" ]]; then
         #If default config file doesn't exist, exit
         echo "$(date): Backup failed (see errors.log)" >> $LOG
         echo "Backup failed"
         echo "Error: Configuration file not found" | tee $ERR
         
         #Fix ownership and permissions of log files if needed
         if [[ ! -z $USER ]]; then
            chown $USER:$USER $LOG && chmod 644 $LOG
            chown $USER:$USER $ERR && chmod 644 $ERR
            chown $USER:$USER $WARN && chmod 644 $WARN
         fi

         mv $LOG "$HOMEDIR/.simple_backup/simple_backup.log"
         mv $ERR "$HOMEDIR/.simple_backup/errors.log"
         mv $WARN "$HOMEDIR/.simple_backup/warnings.log"

         exit 1
      fi

   else
      CONFIG="$1"

      if [[ ! -f "$CONFIG" ]]; then
         #If the provided configuration file doesn't exist, exit
         echo "$(date): Backup failed (see errors.log)" >> $LOG
         echo "Backup failed"
         echo "Error: Configuration file not found" | tee -a $ERR
         
         #Fix ownership and permissions of log files if needed
         if [[ ! -z $USER ]]; then
            chown $USER:$USER $LOG && chmod 644 $LOG
            chown $USER:$USER $ERR && chmod 644 $ERR
            chown $USER:$USER $WARN && chmod 644 $WARN
         fi
         
         mv $LOG "$HOMEDIR/.simple_backup/simple_backup.log"
         mv $ERR "$HOMEDIR/.simple_backup/errors.log"
         mv $WARN "$HOMEDIR/.simple_backup/warnings.log"

         exit 1
      fi

   fi

   #Create temporary files
   INPUTS=$(mktemp)
   EXCLUDE=$(mktemp)
   BACKUP=$(mktemp)
   NKEEP=$(mktemp)

   #Parse the configuration file
   awk -v INPUTS="$INPUTS" -v EXCLUDE="$EXCLUDE" -v BACKUP="$BACKUP" \
       -v NKEEP="$NKEEP" -v UHOME="$HOMEDIR/" -F '[=,]' \
      '$1=="inputs" { for ( i=2; i<=NF; i++ ) { sub(/^~\//,UHOME,$i); print $i > INPUTS } }
       $1=="backup_dir" { sub(/^~\//,UHOME,$2); print $2 > BACKUP }
       $1=="exclude" { for ( i=2; i<=NF; i++ ) { sub(/^~\//,UHOME,$i); print $i > EXCLUDE } }
       $1=="keep" { if ( $2 != NULL ) { print $2 > NKEEP } }' $CONFIG

   BACKUP_DEV=$(cat $BACKUP)
   KEEP=$(cat $NKEEP)
   
   rm "$BACKUP"
   rm "$NKEEP"

   if [[ -z "$BACKUP_DEV" || ! -d "$BACKUP_DEV" ]]; then
      #If the backup directory is not set or doesn't exist, exit
      echo "$(date): Backup failed (see errors.log)" >> $LOG
      echo "Backup failed"
      echo "Error: Output folder \"$BACKUP_DEV\" not found" | tee -a $ERR
   
      #Fix ownership and permissions of log files if needed
      if [[ ! -z $USER ]]; then
         chown $USER:$USER $LOG && chmod 644 $LOG
         chown $USER:$USER $ERR && chmod 644 $ERR
         chown $USER:$USER $WARN && chmod 644 $WARN
      fi

      mv $LOG "$HOMEDIR/.simple_backup/simple_backup.log"
      mv $ERR "$HOMEDIR/.simple_backup/errors.log"
      mv $WARN "$HOMEDIR/.simple_backup/warnings.log"

      rm "$INPUTS"
      rm "$EXCLUDE"

      exit 1
   fi

   BACKUP_DIR=$BACKUP_DEV/simple_backup
   DATE=$(date +%Y-%m-%d-%H:%M)

   #Create the backup subdirectory using date
   if [[ ! -d "$BACKUP_DIR" ]]; then
      mkdir -p "$BACKUP_DIR/$DATE"
   else
   #If previous backups exist, save link to the last backup
      LAST_BACKUP=$(readlink -f "$BACKUP_DIR/last_backup")
      mkdir "$BACKUP_DIR/$DATE"
   fi

   #Set the backup directory variable to the newly created subfolder
   BACKUP_DIR="$BACKUP_DIR/$DATE"

   n_in=$(cat $INPUTS | wc -l)
   
   return
}

#Parse options
function parse_options {
   n_in=0
   
   #Create a temporary file to store inputs
   INPUTS=$(mktemp)
   #Create temp file to store exclude patterns
   EXCLUDE=$(mktemp)

   while [[ "$#" -gt 0 ]]
   do
      var="$1"

      case "$var" in
         -h | --help)
            help_function

            rm $INPUTS
            rm $EXCLUDE

            exit 0
            ;;

         -i | --input)

            while [[ "$#" -gt 1 && ! "$2" =~ ^- ]]
            do
               input="$2"

               if [[ ! -e "$input" ]]; then
                 echo "Warning: input \"$input\" not found. Skipping" | tee -a $WARN
               else
                  n_in=$((n_in+1))
                  echo "$input" >> "$INPUTS"
               fi

               shift
            done

            ;;

         -d | --directory)
            BACKUP_DEV="$2"

            if [[ -z "$BACKUP_DEV" || ! -d "$BACKUP_DEV" ]]; then
               echo "$(date): Backup failed (see errors.log)" >> $LOG
               echo "Backup failed"
               echo "Error: output folder \"$BACKUP_DEV\" not found" | tee -a $ERR

               #Fix ownership and permissions of log files if needed
               if [[ ! -z $USER ]]; then
                  chown $USER:$USER $LOG && chmod 644 $LOG
                  chown $USER:$USER $ERR && chmod 644 $ERR
                  chown $USER:$USER $WARN && chmod 644 $WARN
               fi

               mv $LOG "$HOMEDIR/.simple_backup/simple_backup.log"
               mv $ERR "$HOMEDIR/.simple_backup/errors.log"
               mv $WARN "$HOMEDIR/.simple_backup/warnings.log"

               rm $INPUTS
               rm $EXCLUDE

               exit 1
            fi

            BACKUP_DIR="$BACKUP_DEV/simple_backup"
            DATE=$(date +%Y-%m-%d-%H:%M)

            #Create the backup subdirectory using date
            if [[ ! -d "$BACKUP_DIR" ]]; then
               mkdir -p "$BACKUP_DIR/$DATE"
            else
               #If previous backup(s) exist(s), save link to the last backup
               LAST_BACKUP=$(readlink -f "$BACKUP_DIR/last_backup")
               mkdir "$BACKUP_DIR/$DATE"
            fi

            #Set the backup directory variable to the newly created subfolder
            BACKUP_DIR="$BACKUP_DIR/$DATE"
            shift
            ;;

         -e | --exclude)
            while [[ "$#" -gt 1 && ! "$2" =~ ^- ]]
            do
               echo "$2" >> "$EXCLUDE"
               shift
            done
            ;;

         -k | --keep)
            KEEP="$2"
            shift
            ;;

         -c | --config)
               rm "$EXCLUDE"
               rm "$INPUTS"

            read_conf "$2"
            return
            ;;

         -u | --user)
               if [[ ! -d "/home/$2" ]]; then
                  echo "$(date): Backup failed (see errors.log)" >> $LOG
                  echo "Backup failed"
                  echo "Error: user $2 doesn't exist" | tee -a $ERR
                  
                  if [[ ! -d "$HOMEDIR/.simple_backup" ]]; then
                     mkdir "$HOMEDIR/.simple_backup"
                  fi

                  #Fix ownership and permissions of log files if needed
                  if [[ ! -z $USER ]]; then
                     chown $USER:$USER $LOG && chmod 644 $LOG
                     chown $USER:$USER $ERR && chmod 644 $ERR
                     chown $USER:$USER $WARN && chmod 644 $WARN
                  fi

                  mv $LOG "$HOMEDIR/.simple_backup/simple_backup.log"
                  mv $ERR "$HOMEDIR/.simple_backup/errors.log"
                  mv $WARN "$HOMEDIR/.simple_backup/warnings.log"

                  exit 1
               fi

               if [[ ! -d "/home/$2/.simple_backup" ]]; then
                  mkdir "/home/$2/.simple_backup"

                  echo "Created directory \"$HOMEDIR/.simple_backup\"." 
               fi

               HOMEDIR="/home/$2"
               USER="$2"
               
               shift
            ;;

         *)
            echo "$(date): Backup failed (see errors.log)" >> $LOG
            echo "Backup failed"
            echo "Error: Option $1 not recognised. Use 'simple-backup -h' to see available options" | tee -a $ERR

            #Fix ownership and permissions of log files if needed
            if [[ ! -z $USER ]]; then
               chown $USER:$USER $LOG && chmod 644 $LOG
               chown $USER:$USER $ERR && chmod 644 $ERR
               chown $USER:$USER $WARN && chmod 644 $WARN
            fi

            mv $LOG "$HOMEDIR/.simple_backup/simple_backup.log"
            mv $ERR "$HOMEDIR/.simple_backup/errors.log"
            mv $WARN "$HOMEDIR/.simple_backup/warnings.log"

            exit 1
            ;;
      esac

      shift
   done

   return
}

#Create temporary log files
LOG=$(mktemp)
ERR=$(mktemp)
WARN=$(mktemp)

HOMEDIR="$HOME"
OPTIONS="-arvh -H -X -R" 

#Check number of parameters
if [[ "$#" -eq 0 ]]; then
   if [[ ! -d "$HOMEDIR/.simple_backup" ]]; then
      mkdir "$HOMEDIR/.simple_backup"

      echo "Created directory \"$HOMEDIR/.simple_backup\"." 
      echo "Copy there sample configuration and edit it"
      echo "to your needs before running the backup,"
      echo "or pass options on the command line."

      exit 1
   fi

   read_conf
else
   parse_options $@

   if [[ $n_in -gt 0 && ( -z $BACKUP_DIR || ! -d $BACKUP_DIR ) ]]; then
      #If the backup directory is not set or doesn't exist, exit
      echo "$(date): Backup failed (see errors.log)" >> $LOG
      echo "Backup failed"
      echo "Error: Output folder \"$BACKUP_DEV\" not found" | tee -a $ERR
   
      #Fix ownership and permissions of log files if needed
      if [[ ! -z $USER ]]; then
         chown $USER:$USER $LOG && chmod 644 $LOG
         chown $USER:$USER $ERR && chmod 644 $ERR
         chown $USER:$USER $WARN && chmod 644 $WARN
      fi

      mv $LOG "$HOMEDIR/.simple_backup/simple_backup.log"
      mv $ERR "$HOMEDIR/.simple_backup/errors.log"
      mv $WARN "$HOMEDIR/.simple_backup/warnings.log"

      exit 1      
   elif [[ $n_in -eq 0 && -z $BACKUP_DIR ]]; then
      if [[ ! -d "$HOMEDIR/.simple_backup" ]]; then
         mkdir "$HOMEDIR/.simple_backup"

         echo "Created directory \"$HOMEDIR/.simple_backup\"." 
         echo "Copy there sample configuration and edit it"
         echo "to your needs before running the backup,"
         echo "or pass options on the command line."

         exit 1
      fi

      read_conf $HOMEDIR/.simple_backup/config
   fi
fi

if [[ $n_in -eq 0 ]]; then
   echo "$(date): Backup finished (no files copied)" >> $LOG
   echo "Backup finished"
   echo "Warning: no valid input selected. Nothing to do" | tee -a $WARN
               
   #Fix ownership and permissions of log files if needed
   if [[ ! -z $USER ]]; then
      chown $USER:$USER $LOG && chmod 644 $LOG
      chown $USER:$USER $ERR && chmod 644 $ERR
      chown $USER:$USER $WARN && chmod 644 $WARN
   fi

   mv $LOG "$HOMEDIR/.simple_backup/simple_backup.log"
   mv $ERR "$HOMEDIR/.simple_backup/errors.log"
   mv $WARN "$HOMEDIR/.simple_backup/warnings.log"

   exit 0
fi

echo "$(date): Starting backup" > $LOG
echo "Starting backup..."

#If specified, keep the last n backups and remove the others. Default: keep all
if [[ -n $KEEP ]]; then
   N_BACKUP=$(ls -l $BACKUP_DEV/simple_backup | grep -c ^d)
   N_BACKUP=$(($N_BACKUP-1))

   if [[ $N_BACKUP -gt $KEEP ]]; then
     echo "$(date): Removing old backups" >> $LOG
      echo "Removing old backups..."
      REMOVE=$(mktemp)
      find $BACKUP_DEV/simple_backup/* -maxdepth 0 -type d | sort | head -n $(($N_BACKUP - $KEEP)) >> $REMOVE

      while read line
      do
         rm -r $line
         echo "Removed backup: $line" >> $LOG
      done<$REMOVE

      echo "Removed old backups"

      rm $REMOVE  
   fi
      
fi

# Sort input files for rsync efficiency
if [[ ! -z "$INPUTS" ]]; then
   sort "$INPUTS" -o "$INPUTS"
fi

echo "Copying files. This may take a long time..."

if [[ -z "$LAST_BACKUP" ]]; then
   rsync $OPTIONS --exclude-from="$EXCLUDE" --files-from="$INPUTS" / "$BACKUP_DIR" --ignore-missing-args >> $LOG 2>> $ERR
else
   rsync $OPTIONS --link-dest="$LAST_BACKUP" --exclude-from="$EXCLUDE" --files-from="$INPUTS" / "$BACKUP_DIR" --ignore-missing-args >> $LOG 2>> $ERR
fi

#Update the logs
if [[ $(cat $ERR | wc -l) -gt 0 ]]; then
   echo "$(date): Backup finished with errors" >> $LOG
   echo "Backup finished with errors"
elif [[ $(cat $WARN | wc -l) -gt 0 ]]; then
   echo "$(date): Backup finished with warnings" >> $LOG
   echo "Backup finished (warnings)"
else
   echo "$(date): Backup finished" >> $LOG
   echo "Backup finished"
fi

#Fix ownership and permissions of log files if needed
if [[ ! -z $USER ]]; then
   chown $USER:$USER $LOG && chmod 644 $LOG
   chown $USER:$USER $ERR && chmod 644 $ERR
   chown $USER:$USER $WARN && chmod 644 $WARN
fi

#Copy log files in home directory
mv $LOG "$HOMEDIR/.simple_backup/simple_backup.log"
mv $ERR "$HOMEDIR/.simple_backup/errors.log"
mv $WARN "$HOMEDIR/.simple_backup/warnings.log"

if [[ ! -z "$EXCLUDE" ]]; then
   rm "$EXCLUDE"
fi

if [[ ! -z "$INPUTS" ]]; then
   rm "$INPUTS"
fi

if [[ -L "$BACKUP_DEV/simple_backup/last_backup" ]]; then
   rm "$BACKUP_DEV/simple_backup/last_backup"
fi

BACKUP_DIR_FULL=$(readlink -f "$BACKUP_DIR")
ln -sf "$BACKUP_DIR_FULL" "$BACKUP_DEV/simple_backup/last_backup"

exit 0